While I haven't used AIDE or Tripwire on Proxmox hosts, I do run Wazuh which performs similar function among other things. I've been using it for years on Proxmox and other servers without any issues.
All emails sent to 'root' are forwarded to that address. So, apt notices, etc. The email address is stored in /etc/pve/user.cfg
Curious, what KVM are you using? I've installed Proxmox via iLO, DRAC, IPMI, and Avocent KVMs many times, without issues.
apcupsd isn't a web server, so it won't work from a browser. If you want a web interface for it, you'll need to setup a web server running the apcupsd CGI scripts, http://www.apcupsd.org/manual/manual.html#apcupsd-network-monitoring-cgi-programs
Probably best to upgrade to latest Gluster 3.7, or 3.8 from the Gluster repo. I recall some fixes recently related to issues with ZFS based bricks. That said, RedHat currently only recommends XFS for bricks.
This is what /etc/network/interfaces looks like on one my hosts.
auto lo
iface lo inet loopback
auto vmbr0
iface vmbr0 inet static
address 192.168.1.10
netmask 255.255.255.0
gateway 192.168.1.1
bridge_ports eth0
bridge_stp off
bridge_fd 0